Self-heating phase change energy storage winding charging cable and preparation method thereof

Abstract

This invention relates to the field of cable technology, and in particular to a self-heating phase change energy storage winding charging cable and its preparation method. From the inside out, the cable comprises a conductor core, an insulation layer, a spiral tensile thermally conductive skeleton, a phase change energy storage thermally conductive layer, a PTC self-regulating heating layer, a thermal insulation layer, and an outer sheath layer. The spiral tensile thermally conductive skeleton is integrally formed with radial thermally conductive fins. A high thermal conductivity carbon fiber mesh is embedded inside the phase change energy storage thermally conductive layer. A temperature sensing layer is provided between the PTC self-regulating heating layer and the phase change energy storage thermally conductive layer. The thermal insulation layer has a double-layer composite structure, and an anti-freeze and wear-resistant buffer layer is provided on the inner side of the outer sheath layer. All layers are coaxially integrated and tightly bonded, forming a closed-loop energy management system. This invention provides long-lasting power-off insulation, completely solving the problem of winding in extremely cold conditions; uniform heating without overheating, significantly improving safety performance; energy saving and consumption reduction, lowering usage and production costs; enhanced mechanical properties, suitable for extremely cold winding scenarios; and intelligent integrated control, requiring no manual intervention.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a self-heating phase change energy storage wound charging cable and its preparation method. Background Technology

[0002] In extremely cold regions of Northeast my country, Xinjiang, and Inner Mongolia, reel-type charging equipment such as outdoor electric vehicle charging piles, industrial mobile equipment, and power supply devices for construction machinery has become widely used. As a core component for power transmission and mobile operations, reel-type charging cables must withstand frequent mechanical actions such as insertion / removal, winding, stretching, and bending. In extremely cold environments, the outer sheaths and insulation materials commonly used in traditional charging cables, such as PVC, neoprene rubber, and ordinary EPDM rubber, undergo a low-temperature glass transition, freezing the molecular chains. This causes the cable to quickly become stiff, brittle, and difficult to bend, making it impossible to smoothly reel in after charging. Forced winding can directly cause cracks in the outer sheath, damage to the insulation layer, and breakage of the internal conductor copper wires. Long-term use can easily lead to serious safety accidents such as insulation breakdown, leakage, and short circuits, causing equipment downtime and operational interruptions, significantly increasing outdoor maintenance costs and safety risks, and severely restricting the stable application of new energy charging and industrial mobile equipment in extremely cold regions.

[0003] Current technical solutions for addressing the lack of low-temperature flexibility in cables in cold regions mainly fall into three categories, all of which suffer from insurmountable technical defects and cannot meet the full-process usage requirements of extremely cold winding scenarios. The external heating cable method passively heats the cable by wrapping resistance wire around it, resulting in poor adhesion between the heating cable and the cable, long heat conduction paths, temperature differences exceeding 15°C, and localized overheating that easily erodes the insulation layer. The resistance wire is prone to fatigue and breakage after repeated bending, leading to a short lifespan. Furthermore, it requires continuous power to maintain temperature, consuming over 50W / m of energy, and relies on manual start / stop, exhibiting low levels of automation. It is also prone to aging and failure in extremely cold outdoor environments, making maintenance cumbersome. The direct conductor heating method relies on the charging current to generate Joule heat in the conductor, only raising the cable temperature during charging. After charging is completed and power is cut off, there is no continuous heat source, causing the cable to cool rapidly within 1-3 minutes at a rate exceeding 8°C / min. By the time it is wound up, it is completely stiff, with a bending modulus exceeding 2000MPa, completely failing to address the core pain point of "winding up after charging." The pure material improvement method simply uses high-end cold-resistant rubber to replace ordinary materials. Although it slightly improves low-temperature flexibility, the improvement in flexibility is limited at extreme low temperatures of -40℃, and the flexural modulus still exceeds 1500MPa. The material cost is more than 30% higher than that of ordinary cables, and it does not have active temperature control and heat storage functions. It does not have the ability to keep warm when the power is off, and it can only passively resist cold. It cannot achieve the long-term heat preservation effect of charging energy storage and releasing heat when the power is off.

[0004] In summary, existing technologies cannot overcome the industry challenges of rapid cooling after power failure and loss of flexibility during winding in extremely cold environments. They also suffer from multiple shortcomings, such as uneven heating, high energy consumption, poor bending resistance, high cost, and insufficient intelligence. These technologies fail to meet the safety, energy-saving, long-term, and stable requirements of wound charging cables in extremely cold regions. There is an urgent need to develop a new type of wound charging cable that combines self-heating, phase change energy storage, intelligent temperature control, and high bending resistance. Summary of the Invention

[0005] The technical problem this invention aims to solve is that cables in extremely cold environments rapidly cool down after being charged and then de-energized, lose flexibility during winding, and suffer from uneven heating, excessive energy consumption, poor bending resistance, high cost, and insufficient intelligence.

[0006] The technical solution adopted by this invention to solve its technical problem is: a self-heating phase change energy storage wound charging cable, comprising, from the inside out, a conductor core, an insulation layer, a spiral tensile thermally conductive skeleton, a phase change energy storage thermally conductive layer, a PTC self-regulating heating layer, a thermal insulation layer, and an outer sheath layer; the spiral tensile thermally conductive skeleton is integrally formed with radial thermally conductive fins, the phase change energy storage thermally conductive layer is embedded with a high thermal conductivity carbon fiber mesh, a temperature sensing layer is provided between the PTC self-regulating heating layer and the phase change energy storage thermally conductive layer, the thermal insulation layer is a double-layer composite structure, and an anti-freeze and wear-resistant buffer layer is provided on the inner side of the outer sheath layer; all layers are coaxially integrated and tightly bonded to form a closed-loop energy management system for heat.

[0007] The conductor core is a layered stranded structure of 7 inner strands and 19 outer strands of tin-plated copper wire, with a single wire diameter of 0.3~0.5mm, a stranding pitch of 8-12 times the conductor diameter, and a conductivity ≥59MS / m.

[0008] The diameter of the steel wire in the spiral tensile thermal conductive skeleton is 0.8-2.0 mm, the pitch is 5-20 mm, the height of the radial thermal conductive fins is 0.5-1 mm, and the thermal conductivity uniformity error is ≤1℃.

[0009] The phase change energy storage thermal conductive layer is composed of paraffin-based microcapsule phase change material, 1-5 wt% graphene, and 3-8 wt% boron nitride, with an energy storage density ≥180 J / g. The pore size of the high thermal conductivity carbon fiber mesh is 2-5 mm.

[0010] The temperature sensing layer is a flexible thin film with an integrated NTC thermistor, with a thickness of 0.1-0.3 mm and a temperature response time of ≤0.5 s.

[0011] The thermal insulation layer comprises an inner layer of aerogel felt and an outer layer of cross-linked polyethylene foam, with an overall thermal conductivity ≤0.02W / (m·K) and a thermal insulation efficiency ≥92%.

[0012] The antifreeze and wear-resistant buffer layer is made of cold-resistant silicone rubber with a thickness of 1-2mm; the outer sheath layer has a Shore hardness of ≤80A, a flexural modulus of ≤750MPa, and a bending cycle of ≥150,000 times at -40℃.

[0013] The PTC self-regulating heating layer has a Curie temperature of 4-6℃, a rated heating power of 5-20W / m, and a heating uniformity error of ≤2℃.

[0014] A method for preparing a self-heating phase change energy storage wound charging cable includes the following steps: conductor layer stranding → insulation layer extrusion → finned spiral skeleton winding → vacuum impregnation and filling of phase change layer → composite temperature sensing layer and PTC layer → double-layer heat insulation layer extrusion → buffer layer and outer sheath extrusion → finished product testing.

[0015] The vacuum impregnation and filling phase change layer has a density of ≥99%, a preheating and curing temperature of 60-80℃, and a time of 10-15 minutes; the cable is suitable for scenarios with a winding reel diameter of ≥300mm and a winding length of 10-50m.

[0016] The beneficial effects of this invention are: (1) This invention utilizes the latent heat storage and heat release characteristics of the phase change energy storage and heat conduction layer, combined with the efficient heat-locking of the double-layer heat insulation layer. After charging, there is no need to continuously supply power, and the cable can be maintained in the flexible range of 0-10℃ for 30-50 minutes, completely covering the entire winding process. The cable bending modulus is ≤750MPa in the -40℃ environment, which is more than 50% more flexible than traditional cold-resistant cables, fundamentally solving the problem of cables becoming stiff and unable to be wound after charging in extremely cold environments.

[0017] (2) The spiral tensile thermal conductive skeleton is combined with radial thermal conductive fins and high thermal conductivity carbon fiber mesh to achieve uniform heat conduction in the axial and radial directions, with a thermal uniformity error of ≤1℃; the temperature sensing layer and the PTC self-limiting heating layer are linked to control the temperature, with a response time of ≤0.5s, eliminating temperature control lag and local overheating, and the cable can withstand ≥150,000 bends without structural damage, and its service life is 3 times longer than that of ordinary cold-region cables.

[0018] (3) The PTC self-limiting heating layer only needs short-term preheating, and the overall energy consumption is reduced by more than 70% compared with the external heat tracing method. The vacuum impregnation filling process is adopted, the phase change layer density is ≥99%, there is no leakage or bubbles, and the material cost is reduced by 25% compared with the pure material improvement method, which is suitable for large-scale industrial production.

[0019] (4) The spiral tensile thermal conductive skeleton has a tensile strength of ≥1200N. Combined with the anti-freeze and wear-resistant buffer layer on the inner side of the outer sheath, it achieves an integrated upgrade of tensile strength, bending resistance and weather resistance. When the cable bending radius is ≤5 times the outer diameter, there is no deformation or breakage, which perfectly meets the high-frequency winding requirements of the charging pile winding disc.

[0020] (5) The cable is linked with the low-voltage auxiliary power supply and control module of the charging pile to automatically complete the switching of three modes: charging preheating, charging heat preservation, and power-off heat release and winding. No manual operation is required throughout the process. It has a high degree of intelligence and is suitable for outdoor extreme cold unattended scenarios. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] In the figure: 1. Conductor core; 2. Insulation layer; 3. Spiral tensile thermally conductive skeleton; 31. Radial thermally conductive fins; 4. Phase change energy storage thermally conductive layer; 41. High thermal conductivity carbon fiber mesh; 5. PTC self-limiting heating layer; 51. Temperature sensing layer; 6. Thermal insulation layer; 61. Aerogel felt inner layer; 62. Cross-linked polyethylene foam outer layer; 7. Outer sheath layer; 71. Antifreeze and wear-resistant buffer layer. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Figure 1 As shown, the self-heating phase change energy storage coiled charging cable of the present invention has a coaxial integrated structure, consisting of conductor core 1, insulation layer 2, spiral tensile thermal conductive skeleton 3, phase change energy storage thermal conductive layer 4, PTC self-limiting heating layer 5, heat insulation layer 6, and outer sheath layer 7 from the inside out. The spiral tensile thermal conductive skeleton 3 has radial thermal conductive fins 31 integrally formed on the outside. The phase change energy storage thermal conductive layer 4 has a high thermal conductivity carbon fiber mesh 41 embedded inside. A temperature sensing layer 51 is provided between the PTC self-limiting heating layer 5 and the phase change energy storage thermal conductive layer 4. The heat insulation layer 6 is composed of an aerogel felt inner layer 61 and a cross-linked polyethylene foam outer layer 62. The outer sheath layer 7 has an anti-freeze and wear-resistant buffer layer 71 on the inside. All layers are tightly bonded without gaps.

[0027] Conductor core 1 is made of tin-plated copper wire with an inner layer of 7 strands and an outer layer of 19 strands, with a single wire diameter of 0.3 mm and a stranding pitch of 10 times the conductor diameter. It has a conductivity of 59 MS / m and generates 10 W / m of Joule heat during charging, providing the basic heat source for the cable. Insulation layer 2 is made of highly flexible ethylene propylene rubber extruded and is 3 mm thick, with a volume resistivity of 1×10⁻⁶. 14 It has a strength of Ω·m and a breakdown field strength of 22kV / mm, and combines insulation protection with rapid heat conduction.

[0028] The spiral tensile thermal conductive skeleton 3 is made of galvanized steel wire with a diameter of 1.2mm spirally wound with a pitch of 10mm. The radial thermal conductive fins 31 have a height of 0.8mm, a tensile strength of 1200N, and a thermal conductivity uniformity error of ≤1℃, achieving both high tensile strength and uniform thermal conductivity. The phase change energy storage thermal conductive layer 4 is 4mm thick and is made of paraffin-based microcapsule phase change material, 3wt% graphene, and 5wt% boron nitride composite, with an energy storage density of 180J / g. The internally embedded high thermal conductivity carbon fiber mesh 41 has a pore size of 3mm, improving thermal conductivity and energy storage stability.

[0029] The temperature sensing layer 51 is a flexible thin film integrating an NTC thermistor, with a thickness of 0.2 mm and a temperature response time of 0.3 s. It monitors the cable temperature in real time and controls the PTC self-regulating heating layer 5 in conjunction with it. The PTC self-regulating heating layer 5 has a thickness of 1.5 mm, a Curie temperature of 5℃, a rated heating power of 12 W / m, and a heating uniformity error of ≤2℃. It is powered by the 12V low-voltage auxiliary power supply of the charging pile.

[0030] The thermal insulation layer 6 has a total thickness of 3mm, with an inner aerogel felt layer 61 of 1mm thickness and an outer cross-linked polyethylene foam layer 62 of 2mm thickness. The overall thermal conductivity is 0.02W / (m·K), achieving a thermal insulation efficiency of 92%, effectively locking in the cable's internal heat. The freeze-resistant and wear-resistant buffer layer 71 is made of cold-resistant silicone rubber with a thickness of 1.5mm. The outer sheath layer 7 is made of ultra-low temperature cold-resistant TPU material with a thickness of 4mm. At -40℃, it has a Shore hardness of 80A, a flexural modulus of 750MPa, and can withstand 150,000 bends without cracking.

[0031] The cable of this invention operates in three stages: First, in the charging preheating mode, after the charging gun is inserted, the temperature sensing layer 51 triggers the PTC self-regulating heating layer 5 to energize and generate heat, which, combined with the Joule heat of the conductor core 1, allows the phase change energy storage heat conduction layer 4 to complete heat storage within 10 minutes, raising the cable temperature to the 0-10℃ flexible range. Second, in the charging heat preservation mode, when the cable temperature reaches 5℃, the PTC self-regulating heating layer 5 automatically de-energizes and automatically restarts when the temperature drops below -5℃, allowing the phase change energy storage heat conduction layer 4 to continuously store heat until complete phase change. Third, in the power-off heat release and winding mode, after the charging gun is pulled out, the PTC self-regulating heating layer 5 de-energizes, and the phase change energy storage heat conduction layer 4 undergoes a liquid-solid reverse phase change heat release. Combined with the heat insulation layer 6, this maintains the cable's flexible temperature for 30-50 minutes, completing the winding operation.

[0032] The specific steps of the preparation method of the self-heating phase change energy storage wound charging cable of the present invention are as follows: Conductor layer stranding: Tinned copper wire is stranded in layers of 7 inner strands and 19 outer strands to form conductor core 1; Insulation layer extrusion: Insulation layer 2 is extruded using highly flexible ethylene propylene rubber at 190℃, with the thickness controlled at 3mm; Finned spiral skeleton winding: Galvanized steel wire with radial heat-conducting fins 31 is spirally wound with a tension of 60N to form a spiral tensile heat-conducting skeleton 3; Vacuum impregnation filling phase change layer: The phase change composite material is filled into the gaps in the skeleton through a vacuum impregnation process, and preheated and cured at 70°C for 12 minutes, achieving a phase change layer density of 99%; Composite temperature sensing layer and PTC layer: After bonding the temperature sensing layer 51, wrap the PTC self-limiting heating layer 5 to ensure no gaps and no overlap; Double-layer insulation extrusion: the inner aerogel felt layer 61 and the outer cross-linked polyethylene foam layer 62 are extruded sequentially at an extrusion temperature of 130℃. Buffer layer and outer sheath extrusion: First, extrude the antifreeze and wear-resistant buffer layer 71, then extrude the outer sheath layer 7, with an extrusion temperature of 170℃; Finished product testing: The conductivity, insulation, thermal conductivity and energy storage performance, and low-temperature flexibility of the cable are tested. Once the test results meet the standards, the cable is considered a finished product.

[0033] Testing showed that the cable of this invention can maintain its flexibility for 35 minutes after power failure in an extremely cold environment of -40℃, with a bending modulus ≤750MPa and tensile strength ≥1200N, fully meeting the usage requirements of winding charging scenarios in extremely cold regions.

[0034] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A self-heating phase change energy storage wound charging cable, characterized in that, From the inside out, the structure consists of a conductor core (1), an insulation layer (2), a spiral tensile thermally conductive skeleton (3), a phase change energy storage thermally conductive layer (4), a PTC self-regulating heating layer (5), a thermal insulation layer (6), and an outer sheath layer (7). The spiral tensile thermally conductive skeleton (3) is integrally formed with radial thermally conductive fins (31). The phase change energy storage thermally conductive layer (4) has a high thermal conductivity carbon fiber mesh (41) embedded inside. A temperature sensing layer (51) is provided between the PTC self-regulating heating layer (5) and the phase change energy storage thermally conductive layer (4). The thermal insulation layer (6) is a double-layer composite structure. The outer sheath layer (7) has an anti-freeze and wear-resistant buffer layer (71) on its inner side. All layers are coaxially integrated and tightly bonded to form a closed-loop energy management system for heat.

2. The cable according to claim 1, characterized in that, The conductor core (1) is a layered stranded structure of tin-plated copper wire with 7 inner strands and 19 outer strands. The diameter of a single wire is 0.3~0.5mm, the stranding pitch is 8-12 times the conductor diameter, and the conductivity is ≥59MS / m.

3. The cable according to claim 1, characterized in that, The diameter of the steel wire in the spiral tensile thermal conductive skeleton (3) is 0.8-2.0 mm, the pitch is 5-20 mm, the height of the radial thermal conductive fins (31) is 0.5-1 mm, and the thermal uniformity error is ≤1℃.

4. The cable according to claim 1, characterized in that, The phase change energy storage thermal conductive layer (4) is composed of paraffin-based microcapsule phase change material, 1-5 wt% graphene, and 3-8 wt% boron nitride, with an energy storage density ≥180 J / g. The pore size of the high thermal conductivity carbon fiber mesh (41) is 2-5 mm.

5. The cable according to claim 1, characterized in that, The temperature sensing layer (51) is a flexible thin film with an integrated NTC thermistor, with a thickness of 0.1-0.3 mm and a temperature response time of ≤0.5 s.

6. The cable according to claim 1, characterized in that, The thermal insulation layer (6) includes an aerogel felt inner layer (61) and a cross-linked polyethylene foam outer layer (62), with an overall thermal conductivity ≤0.02W / (m·K) and a thermal insulation efficiency ≥92%.

7. The cable according to claim 1, characterized in that, The antifreeze and wear-resistant buffer layer (71) is made of cold-resistant silicone rubber with a thickness of 1-2mm; the outer sheath layer (7) has a Shore hardness of ≤80A, a flexural modulus of ≤750MPa, and a bending cycle of ≥150,000 times at -40℃.

8. The cable according to claim 1, characterized in that, The PTC self-limiting heating layer (5) has a Curie temperature of 4-6℃, a rated heating power of 5-20W / m, and a heating uniformity error of ≤2℃.

9. A method for preparing a self-heating phase change energy storage wound charging cable according to any one of claims 1-8, characterized in that, Includes the following steps: Conductor layer stranding → insulation layer extrusion → finned spiral skeleton winding → vacuum impregnation and filling phase change layer → composite temperature sensing layer and PTC layer → double-layer heat insulation layer extrusion → buffer layer and outer sheath extrusion → finished product inspection.

10. The preparation method according to claim 9, characterized in that, The vacuum impregnation and filling phase change layer has a density of ≥99%, a preheating and curing temperature of 60-80℃, and a time of 10-15 minutes; the cable is suitable for scenarios with a winding reel diameter of ≥300mm and a winding length of 10-50m.

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